1. Field of the Invention
This invention relates to a semiconductor device. This invention particularly relates to a semiconductor device capable of wireless data communication, a so-called IC chip (also referred to as an ID chip or a transponder) for RFID (radio frequency identification).
Note that the semiconductor device herein means all devices that can function by utilizing the semiconductor characteristics.
2. Description of the Related Art
In recent years, an environment in which it is possible to access an information network anytime and anywhere, as it is called ubiquitous information society, has been put into place. In such environment, an individual identification technique in which an ID (individual identification number) is given to an individual object to clarify records of the object so that it is useful for production, management, and the like has been researched for practical use. In particular, semiconductor devices (hereinafter referred to as semiconductor devices and also referred to as ID chips, IC chips, and transponders) which utilize an RFID (radio frequency identification) technique and performs wireless data communication with external communication devices (hereinafter referred to as communication devices, and also referred to as reader/writers, controllers, and interrogators) have become widely used.
A semiconductor device receives a wireless signal, which is transmitted from a communication device, with an antenna. Being an AC voltage signal (hereinafter referred to as an AC signal), the wireless signal is converted into a DC voltage signal (hereinafter referred to as a DC signal) by a rectifier circuit for rectification. The DC signal is input to a constant voltage circuit (also referred to as a regulator or a power supply circuit) so that power supply voltage Vdd is generated. The power supply voltage Vdd generated in the constant voltage circuit is supplied to a plurality of circuits included in the semiconductor device.
As a rectifier element in a semiconductor device, which forms a rectifier circuit for supplying a DC signal to a constant voltage circuit, a rectifier element formed using a transistor a gate of which is in electrical connection with one of source and drain terminals, a so-called diode-connected transistor, can be given for cost reduction. Patent Document 1 (Japanese Published Patent Application No. 2002-152080) discloses a structure with a transistor which is diode-connected and provided in a rectifier circuit in a semiconductor device.